Fuel cell power plant fuel control
AssigneeInternational Fuel Cells Corporation
InventorGlenn W. Scheffler
Life of this patent
Estimating the term…
Abstract
Fuel cell current is sensed (30) and during a transient, a feed forward demand signal (50) sent to the fuel flow regulator (58). A nominal desired reformer temperature is established for the new fuel cell current. This desired temperature signal (62) is dynamically compensated (64) to establish the operating temperature set point (72). A predominantly lead compensation (66) is achieved for a desired temperature increase and a predominantly lag compensation (68) for a desired temperature decrease. Increased reliance on the temperature as a result of the system input reduces reliance on the accuracy of fuel flow measurement and on the consistency of fuel heating value.
Claims4
In a fuel cell power plant having, fuel supply means for supplying a flow of fuel, a reformer receiving and reforming said flow of fuel, a fuel stack receiving fuel from said reformer, a conduit for conveying fuel cell exhaust containing excess hydrogen to said reformer, a burner for burning said exhaust and said reformer in heat exchange relationship with the fuel supply passing through said reformer;
- a control system comprising:
- a current sensor for sensing the electrical load on said fuel cell stack and establishing a current sensed signal;
- a fuel flow summation point;
- means for conducting said current sensed signal to said fuel flow summation point as a nominal desired fuel flow signal;
- a temperature sensor for sensing the temperature of the reformed fuel at said reformer and establishing a temperature sensed signal;
- a first function generator for setting a nominal desired reformer fuel temperature set point representing the steady state desired temperature as a function of the sensed current;
- a dynamic compensator for modifying said desired reformer fuel temperature set point to obtain a transient temperature set point comprising, a first lead/lag compensator, a second lead/lag, compensator, one of said lead/lag compensators generating a predominantly lead characteristic signal and the other generating a predominantly lag characteristic signal, and a high select component for selecting and passing the higher signal of said lead characteristic signal and said lag characteristic signal;
- error means for comparing said higher signal with said sensed temperature signal and establishing a temperature error signal;
- means for modifying said nominal desired fuel flow signal as a function of by said temperature error signal and establishing a transient desired fuel flow set point signal to said fuel flow summation point;
- fuel flow sensing means for establishing a fuel flow sensed signal;
- means for conveying said fuel flow sensed signal to said fuel flow summation point and establishing a fuel flow error signal;
- and
- fuel flow control means responsive to said fuel flow error signal for controlling said fuel flow.
Dependencies are inferred from the claim text.